U.S. patent number 7,050,268 [Application Number 10/720,996] was granted by the patent office on 2006-05-23 for disk drive with read ic chip and write ic chip mounted respectively on suspension and arm.
This patent grant is currently assigned to Fujitsu Limited. Invention is credited to Hideyuki Kikuchi, Kazuo Kobayashi, Masashige Sato.
United States Patent |
7,050,268 |
Kikuchi , et al. |
May 23, 2006 |
Disk drive with read IC chip and write IC chip mounted respectively
on suspension and arm
Abstract
A dedicated read IC chip is mounted on a head suspension. The
dedicated read IC chip is located closer to a read element. A stray
capacitance of a wiring can be reduced. Even if the electric
resistance value of the read element increases, the magnetic
information data of a higher density can be read out. Moreover, the
dedicated read IC chip generates little heat. Even if the dedicated
read IC chip is located on the head suspension, an excessive heat
cannot be transmitted to the head suspension from the dedicated
read IC chip. The mechanical properties and shape of the head
suspension can be maintained as expected.
Inventors: |
Kikuchi; Hideyuki (Kawasaki,
JP), Sato; Masashige (Kawasaki, JP),
Kobayashi; Kazuo (Kawasaki, JP) |
Assignee: |
Fujitsu Limited (Kawasaki,
JP)
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Family
ID: |
11737349 |
Appl.
No.: |
10/720,996 |
Filed: |
November 24, 2003 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20040130823 A1 |
Jul 8, 2004 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/JP01/04388 |
May 25, 2001 |
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Current U.S.
Class: |
360/244.1;
360/264.2; G9B/5.154 |
Current CPC
Class: |
G11B
5/486 (20130101) |
Current International
Class: |
G11B
5/48 (20060101); G11B 21/16 (20060101) |
Field of
Search: |
;360/244.1,264.2 |
References Cited
[Referenced By]
U.S. Patent Documents
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6377411 |
April 2002 |
Katsumata et al. |
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Foreign Patent Documents
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1014342 |
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Jun 2000 |
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EP |
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6-036252 |
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Feb 1994 |
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JP |
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11-185233 |
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Jul 1999 |
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JP |
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2000-207720 |
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Jul 2000 |
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JP |
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2000-339606 |
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Dec 2000 |
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JP |
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2001-068760 |
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Mar 2001 |
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JP |
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2003077233 |
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Mar 2003 |
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JP |
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Primary Examiner: Renner; Craig A.
Attorney, Agent or Firm: Greer, Burns & Crain, Ltd.
Parent Case Text
This is continuation of International PCT Application No.
PCT/JP01/04388, filed May 25, 2001.
Claims
What is claimed is:
1. A disk drive comprising: a head suspension supporting a head
slider at a tip end thereof; a dedicated read IC chip located on
the head suspension and connected to a read element on the head
slider; a swinging arm supporting the head suspension at a tip end
thereof and coupled to a support shaft for relative rotation; and a
dedicated write IC chip located on the swinging arm and connected
to a write element on the head slider.
2. The disk drive according to claim 1, wherein a length of a
wiring connecting the read element to the dedicated read IC chip is
set shorter than a length of a wiring connecting the write element
to the dedicated write IC chip.
3. The disk drive according to claim 1, wherein the dedicated read
IC chip is located closer to the head slider than the dedicated
write IC chip is.
4. The disk drive according to claim 1, wherein the read element is
a tunnel-junction magnetoresistive element.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a head suspension assembly
incorporated in a recording disk drive such as a hard disk drive
(HDD). In particular, the invention relates to a head suspension
assembly comprising a head slider supporting at least a read
element, and a head suspension supporting the head slider at the
tip end.
2. Description of the Prior Art
The concept of so-called COS (Chip On Suspension) is well known in
the technical field of a hard disk drive (HDD). The COS utilizes a
so-called head IC (Integrated Circuit) chip fixed on a head
suspension. The head IC chip incorporates a read signal processing
circuit and a write signal processing circuit.
The head IC chip can be located closer to a read element and/or a
write element on the head slider based on the COS. Wirings or lead
wires can be shortened between the read element and the head IC
chip as well as between the write element and the head IC chip. The
stray capacitance of the lead wire can be reduced. The reduction of
the stray capacitance serves to realize the operation of reading
and writing information data at a higher frequency bandwidth.
However, the head IC chip generates a large amount of heat energy.
The heat causes changes in the mechanical properties, such as a
spring constant, the shape, and the like, of the head suspension.
For example, if the spring constant of the head suspension
decreases, the head slider supported on the tip end of the head
suspension suffers from reduction in the flying height. The head
slider is likely to collide against a magnetic recording disk.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a
head suspension assembly capable of reducing the stray capacitance
without losing expected mechanical properties and without suffering
from a change in the shape.
According to a first aspect of the invention, there is provided a
head suspension assembly comprising: a head suspension supporting a
head slider at the tip end; a read signal amplifier circuit located
on the head suspension and connected to a read element on the head
slider; and a write signal amplifier circuit located at a position
spaced from the head suspension and connected to a write element on
the head slider.
The read signal amplifier circuit can be located closer to the read
element in the head suspension assembly. A wiring can be shortened
between the read element and the read signal amplifier circuit. The
stray capacitance of the wiring can thus be reduced. The head
suspension assembly of the type enables establishment of a higher
density of the magnetic information data even if the assembly
employs the read element such a tunnel-junction magnetoresistive
element having a high electric resistance value, for example.
In general, the read signal amplifier circuit solely suffers from a
smaller amount of heat energy as compared with the write signal
amplifier circuit. Even if the read signal amplifier circuit is
located on the head suspension, an excessive heat cannot be
transmitted to the head suspension from the read signal amplifier
circuit. The mechanical properties and the shape of the head
suspension can be maintained as expected. In this case, the read
signal amplifier circuit may be mounted on the head suspension in
the form of an IC chip. Alternatively, the read signal amplifier
circuit may be formed directly on the head suspension.
The length of a wiring connecting the read element to the read
signal amplifier circuit may be set shorter than the length of a
wiring connecting the write element to the write signal amplifier
circuit in the head suspension assembly. The read signal amplifier
circuit may be located closer to the head slider than the write
signal amplifier circuit is.
According to a second aspect of the invention, there is provided a
head suspension assembly comprising: a head suspension supporting a
head slider at the tip end; and a dedicated read IC chip located on
the head suspension and connected to a read element on the head
slider.
The read signal amplifier circuit can be located closer to the read
element in the head suspension assembly. A wiring can be shortened
between the read element and the dedicated read IC chip. The stray
capacitance of the wiring can be reduced. The head suspension
assembly of the type enables establishment of a higher density of
the magnetic information data even if the assembly employs the read
element such a tunnel-junction magnetoresistive element having a
high electric resistance value, for example.
The dedicated read IC chip solely suffers from a smaller amount of
heat energy in the same manner as described above. Even if the
dedicated read IC chip is located on the head suspension, an
excessive heat cannot be transmitted to the head suspension from
the dedicated read IC chip. The mechanical properties and the shape
of the head suspension can thus be maintained as expected.
The head suspension assembly may further comprise a dedicated write
IC chip located at a position spaced from the head suspension and
connected to a write element on the head slider. In this case, the
length of a wiring connecting the read element to the dedicated
read IC chip is preferably set shorter than the length of a wiring
connecting the write element to the dedicated write IC chip. The
dedicated read IC chip may be located closer to the head slider
than the dedicated write IC chip is.
The head suspension assembly may be attached to the tip end of a
swinging arm incorporated in a recording disk drive such as a hard
disk drive (HDD). The swinging arm is allowed to swing about a
support shaft, for example.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present
invention will become apparent from the following description of
the preferred embodiment in conjunction with the accompanying
drawings, wherein:
FIG. 1 is a plan view schematically illustrating the inner
structure of a hard disk drive (HDD);
FIG. 2 is an enlarged plan view schematically illustrating the
structure of a head suspension assembly; and
FIG. 3 is a schematic view of a low pass filter.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 schematically illustrates the inner structure of a hard disk
drive (HDD) 11 as an example of a recording disk drive or storage
device. The HDD 11 includes a box-shaped main enclosure 12 defining
an inner space of a flat parallelepiped, for example. At least one
magnetic recording disk 13 as a recording medium is incorporated
within the inner space. The magnetic recording disk 13 is mounted
on the driving shaft of a spindle motor 14. The spindle motor 14 is
allowed to drive the magnetic recording disk 13 for rotation at a
higher revolution speed such as 7,200 rpm, 10,000 rpm, or the like,
for example. A cover, not shown, is coupled to the main enclosure
12 so as to define the closed inner space between the main
enclosure 12 and the cover itself.
A carriage 16 is also accommodated in the inner space of the main
enclosure 12. The carriage 16 is designed to swing about a vertical
support shaft 15. The carriage 16 comprises a rigid swinging arm 17
extending in the horizontal direction from the vertical support
shaft 15, and ahead suspension assembly 18 attached to the tip end
of the swinging arm 17. The head suspension assembly 18 includes an
elastic suspension 19 extending in the forward direction from the
tip end of the swinging arm 17. As conventionally known, a flying
head slider 21 is supported at the tip end of the elastic
suspension 19. A write element and a read element, both not shown,
are mounted on the flying head slider 21. The write head may be a
thin film head capable of writing magnetic information data onto
the magnetic recording disk 13. The read element may be a
tunnel-junction magnetoresistive (TMR) element capable of reading
magnetic information data from the magnetic recording disk 13.
The elastic suspension 19 serves to urge the flying head slider 21
toward the surface of the magnetic recording disk 13. When the
magnetic recording disk 13 rotates, the flying head slider 21 is
allowed to receive airflow generated along the rotating magnetic
recording disk 13. The airflow serves to generate a positive
pressure or lift on the flying head slider 21. The flying head
slider 21 is thus allowed to keep flying above the surface of the
magnetic recording disk 13 during the rotation of the magnetic
recording disk 13 at a higher stability established by the balance
between the urging force of the elastic suspension 19 and the
lift.
When the carriage 16 is driven to swing about the support shaft 15
during the flight of the flying head slider 21, the flying head
slider 21 is allowed to cross the recording tracks defined on the
magnetic recording disk 13 in the radial direction of the magnetic
recording disk 13. This radial movement serves to position the
flying head slider 21 right above a target recording track on the
magnetic recording disk 13. An actuator 22 such as a voice coil
motor (VCM) may serve to realize the swinging movement of the
carriage 16. As conventionally known, in the case where two or more
magnetic recording disks 13 are incorporated within the inner space
of the main enclosure 12, the swinging arm 17 may hold a pair of
the head suspension assembly 18 between the adjacent magnetic
recording disks 13.
As shown in FIG. 2, a dedicated read IC (Integrated Circuit) chip
25 is mounted on the elastic suspension 19 in the head suspension
assembly 18. A read signal amplifier circuit is established in the
dedicated read IC chip 25. The read signal amplifier circuit is
designed to output amplified read signals. A wiring pattern or lead
wire 26 is formed to extend on the surface of the elastic
suspension 19. The lead wire 26 serves to establish connection
between the read element on the flying head slider 21 and the
dedicated read IC chip 25. A signal processing circuit 27 is
connected to the dedicated read IC chip 25. The signal processing
circuit 27 is located on a controller circuit board incorporated in
the HDD 11, for example.
Likewise, a dedicated write IC chip 28 is mounted on the swinging
arm 17. A write signal amplifier circuit is established in the
dedicated write IC chip 28. The write signal amplifier circuit is
designed to output amplified write signals or an amplified write
current. A wiring pattern or lead wire 29 is formed to seamlessly
extend on the surfaces of the elastic suspension 19 and the
swinging arm 17 so as to establish connection between the write
element on the flying head slider 21 and the dedicated write IC
chip 28. The signal processing circuit 27 is connected to the
dedicated write IC chip 28 in the same manner as described
above.
Now, assume that the magnetic information data is written onto the
magnetic recording disk 13. When the write element on the flying
head slider 21 is opposed to the surface of the magnetic recording
disk 13, the signal processing circuit 27 supplies the write
element with the write current. The write current is amplified at
the write signal amplifier circuit in the dedicated write IC chip
28. The amplified write current is supplied to the write element
through the lead wire 29. The write element generates a magnetic
field based on the supplied write current. The magnetic bit data is
written onto the magnetic recording disk 13 in response to
inversions in the polarization of the magnetic field.
In this case, the write current of approximately 4 mA is amplified
to approximately 40 mA, for example, in the dedicated write IC chip
28. A larger electric current of this magnitude generates a large
amount of heat energy in the dedicated write IC chip 28. However,
the heat energy can be kept within the swinging arm 17. The heat
energy hardly reaches the elastic suspension 19. Accordingly, the
mechanical properties and shape can be maintained as expected in
the elastic suspension 19.
Next, assume that the magnetic information data is read out of the
magnetic recording disk 13. When the read element on the flying
head slider 21 is opposed to the surface of the magnetic recording
disk 13, the read element is allowed to receive a magnetic field
acting from the magnetic recording disk 13. The inversion in the
polarization of the magnetic field induces a variation in the
electric resistance of the read element, for example. Supply of a
sensing electric current to the read element induces a variation in
the voltage appearing at the lead wire 26 in response to the
variation in the electric resistance. The variation of the voltage
appearing at the lead wire 26 is amplified in the read signal
amplifier circuit within the dedicated read IC chip 25. The signal
processing circuit 27 reads the magnetic bit data based on the
amplified variation of the voltage.
When the magnetic bit data is read out, the dedicated read IC chip
25 receives the electric current of approximately 3 mA 5 mA, for
example. The dedicated read IC chip 25 thus generates little heat
energy. The elastic suspension 19 can be prevented from suffering
from a larger amount of heat energy. Accordingly, the mechanical
properties and the shape can be maintained as expected in the
elastic suspension 19.
As shown in FIG. 3, when the magnetic bit data is read at the read
element, a so-called low pass filter 31 is established based on the
electric resistance value 32 of the read element and the stray
capacitance 33 of the lead wire 26. An increase in the electric
resistance value and/or the stray capacitance tends to lower the
cutoff frequency of the low pass filter 31. The lowered cutoff
frequency is an obstacle to establishment of a higher recording
density of the magnetic information data. In particular, the read
element such as a tunnel-junction magnetoresistive element having a
high electric resistance value inevitably leads to a lowered cutoff
frequency.
The length of the lead wire 26 can remarkably be shortened because
the dedicated read IC chip 25 is located on the elastic suspension
19 in the aforementioned head suspension assembly 18. The stray
capacitance 33 of the lead wire 26 can remarkably be reduced.
Accordingly, the cutoff frequency of the low pass filter 31 can be
maintained within a relatively high frequency band. The head
suspension assembly 18 enables establishment of a higher density of
the magnetic information data even if the assembly 18 employs the
read element such a tunnel-junction magnetoresistive element having
a high electric resistance value, for example.
It should be noted that the write element and the dedicated write
IC chip 28 may be omitted from the head suspension assembly 18.
* * * * *